1. Field of the Invention
This invention relates generally to a fuel injection valve assembly for use in a reciprocating gas engine and more particularly to a replaceable valve cartridge for use in a fuel injection system for a reciprocating gas engine.
2. Description of the Prior Art
For reciprocating engines that operate by internal combustion of a gaseous fuel such as natural gas, fuel injection valve assemblies are critical components. Typically, each combustion cylinder of such a reciprocating engine has a fuel injection valve assembly, the smooth operation of which is necessary for safe and efficient running of the engine.
These fuel injection valve assemblies require frequent repair due to such problems as deterioration of valve packing or development of a defective valve element. These frequent repairs have proved to be costly and time-consuming. Typically, these repairs have required the engine user to remove the entire valve assembly from the engine block and to send the entire assembly to the manufacturer for reworking or rebuilding. This requirement, of course, has resulted in long periods of engine downtime.
The prior art has attempted to alleviate some of the problems associated with these fuel injection valve assemblies by providing a valve cartridge containing the valve, valve seat, valve stem, and critical packing elements needing frequent replacement or repair. The introduction of this valve cartridge construction for fuel injection valve assemblies has allowed for the shipping, repairing, and stocking of the valve cartridges rather than the very much bulkier total valve assemblies.
A typical prior art fuel injection valve assembly of the cartridge type comprises a valve cage, a valve cartridge, a keeper ring, and an external spring. The valve cage is usually the largest component of the assembly and supports the other components as the assembly is mounted on the engine body. The prior art valve cage has a cartridge-receiving bore therein for receiving the valve cartridge through the end of the bore nearer the inside the engine. When completely assembled with the other components, the cartridge is held in place by the keeper ring that is attached to the valve stem at the end of the cartridge nearer the outside of the engine. The external spring is located between the keeper ring and the valve cage so as to bias the valve in the closed position. The entire assembly is adapted for mounting on the body of the engine by the insertion of cylindrical lower portions of the valve cage and valve cartridge into an opening in the engine body leading to a combustion chamber. Because the prior art valve cage has a cartridge-receiving bore therein for receiving the valve cartridge through the end of the bore nearer the inside of the engine, the valve cartridge must be placed in the valve cage before the valve assembly can be inserted into the engine.
The prior art valve cartridge usually comprises a stem housing, a valve seat at the end of the stem housing nearer the engine, and a valve having a valve face adapted to fit tightly against the face of the valve seat and a valve stem attached to the valve face portion and passing through the stem housing. The valve seat is typically welded to the stem housing and often has a diameter greater than the diameter of the cartridge-receiving bore in the cage.
In all instances known, the prior art valve cartridges are sealed against their respective valve cages by means of a gasket placed between the end of the cage nearer the inside of the engine and a corresponding portion of the valve cartridge equal in diameter to the end of the valve cage. Such a prior art fuel injection valve assembly is manufactured by Wesco Valve & Manufacturing Company, of Marshall, Tex.
An inherent disadvantage in the typical prior art fuel injection valve assemblies is that the entire assembly, including the cage, must be removed anytime a repair is required to any element of the assembly. Since most repairs are required on components of the valve cartridge, it would be advantageous to provide a valve assembly whereby the valve cartridge may be removed from the body of the engine without the necessity of also removing the valve cage.
Several patents have dealt with the general feature of removeability with regard to fuel injection assemblies. However, all of these patents are directed to fuel injection nozzles of the pencil type, that is, the type normally used in diesel engines, an environment totally different from the gas engines where the present invention is used. U.S. Pat. No. 3,924,583 to Jardin discloses an improved mounting apparatus for a diesel fuel injection nozzle to permit selective withdrawal of the nozzle from the engine. U.S. Pat. Nos. 3,791,591 and 3,717,305 both to Hedges disclose improved fuel injection nozzle arrangements which are specifically designed to facilitate the removal of the fuel injection system for replacement and maintenance purposes. Other patents also directed to fuel injection nozzles are U.S. Pat. No. 4,111,370 to Chelgren, U.S. Pat. No. 3,827,638 to Halvorsen, U.S. Pat. No. 3,705,693 to Franz, and U.S. Pat. No. 3,279,706 to Kennedy.